In known installations of hot water, in order to obtain, after opening the tap, water at a desired temperature it was required to maintain the continuous water circulation or control the power of the pump actuating the circulation by means of a timer or a temperature sensor.
The device is known, for example from Polish patent description P.182897, that regulates the temperature of domestic hot water where a temperature sensor is placed in the secondary circuit of the heat exchanger, said sensor is placed on the outlet side of the heat exchanger. The sensor is connected with a regulator, and on the feeding pipe of the secondary heat circuit there is a flow sensor for detection of momentary water flow changes.
Turbine flowmeter is also known from published Polish patent description No. P.110740, that consist of a body, bearing a rotary wheel with paddles, and permanent magnet pulse generator. Pulse generator consists of annular permanent magnet set on the shaft of the rotor and a magnetic field sensor, where both those elements are set close to each other inside of the body, while the magnetic field sensor is connected with a flow volume meter placed outside of the body.
A method for enforcing hot water circulation is known from patent description No. DE19600465, characterized in that the sensor placed in the hot water circulation pipe detects the movement of water in the pipe, and on that basis an impulse to turn the pump on is generated. The hot water installation is characterized in that the sensor detecting the flow of water is a flowmeter, ultrasonic sensor, pressure sensor or a sensor to detect pressure changes and is installed in the hot water pipe, and the impulse to turn the pump on generator is a time switch.